Suspended ceilings have been utilized in building installations for many years. They are typically provided as a grid work of main runners and cross runners suspended from the building structure and supporting suitable infill material such as ceiling tiles, light fixtures, air handling devices, etc. In most suspended ceilings the runners have the form of an inverted "T", and thus, are sometimes called main tee's and cross tee's. The grid tee's are usually formed from a strip of material which has been bent to form a bulb or bead along the top edge of a central web with opposed, outwardly extending flanges located at the bottom edge of the web. The flanges are generally covered by a cap strip to provide a finished appearance to the portion of the tee which is exposed to the room.
Suspended ceilings are generally formed by hanging main tee's along one dimension of a room, the main tee's being spaced apart a distance equal to the length of a cross tee which is typically four feet. The main tees are provided with openings at a regular spacing along the length of the main tee, the openings accepting an end connector located at the end of the cross tee for connecting the cross tee to the main tee. Typically opposed cross tees are interconnected within the opening, the opposed cross tees extending to either side of the web of the main tee. The connection between the cross tee and the main tee and between interconnected cross tees must, according to many present building code standards, be able to support the ceiling in an emergency situation, such as fire and seismic conditions. Thus, the suspended ceiling must provide sufficient integrity such that the connectors will not disengage when exposed to a fire, and also should have sufficient integrity so that in a seismic occurrence, such as an earth quake, the connections will be maintained to enable the infill material of the ceiling to be supported.
A variety of end connector designs have been proposed, the most common of which are stab-in type connectors shown in, for example, U.S. Pat. Nos. 4,108,563 4,611,453 and 4,601,153 amongst others. These stab-in type connectors utilize a tab lanced out of the side of the end connector to engage the side of the web of the main tee adjacent the opening and generally include an interlock to lock two of the end connectors together when placed through the opening from opposite sides of the web of the main tee. While these cross tee connectors were simple to install, in circumstances where it may be desirable to remove the end connector, such end connectors were not easily removed without causing damage to the end connector or the web of the main tee.
In recent years, a number of removable end connectors have been proposed exemplified by U.S. Pat. Nos. 4,648,230 4,779,394 and 5,517,796. While the cross tee connectors of these patent were able to be removed without the use of tools, the removal of the end connectors caused damage to the main tee, both in deformation of the flange of the main tee as well as in deformation of the opening in the main tee for the connection of the connectors.
There thus remains a need for a simple to install cross tee end connector which provides for a secure connection of the cross tees in the suspended ceiling system, while allowing relatively simple removal of the cross tees without damage to the main tee's.